Non-invasive imaging technologies allow images of the internal structures of a patient or object to be obtained without performing an invasive procedure on the patient or object. Technologies such as computed tomography (CT) use various physical principals, such as the differential transmission of x-rays through the target volume, to acquire image data and to construct tomographic images (e.g., three-dimensional representations of the interior of the human body or of other imaged structures).
Imaging moving bodies, such as the heart, presents problems in terms of obtaining clear images of the bodies during movement. Currently, the periodic movement of a heart is accounted for in cardiac imaging by predicting when the cardiac motion will be the smallest and then acquiring data during a range larger than the minimum duration required, to allow for errors in the prediction of the time interval with least motion, and to allow for deviations from strictly periodic motion. Images can be reconstructed from multiple times intervals within the data acquisition window. Image slices or volumes generated from data acquired during these different phases will show different amounts of motion. To obtain a clear image of the heart when the movement of the heart is reduced or temporarily eliminated, the many image slices may be acquired over a significant portion of a cardiac cycle.
For example, the heart rate of a patient can be determined. A significant portion of the cardiac cycle (e.g., from 35% to 85% of the R-R interval) can be used for a data acquisition window. The heart is exposed to x-rays during this time. This significant portion of the cardiac cycle can result in significant exposure of the heart and surrounding tissue to potentially damaging x-rays. Additionally, if the patient has an irregular heart rate, this acquisition window can be increased, which also results in significant exposure of the heart and surrounding tissue to potentially damaging x-rays.
A need exists to improve imaging of moving bodies, such as hearts, to obtain clear images of the moving bodies while movement of the bodies is reduced or eliminated, while also reducing exposure of the patient to x-rays used to acquire the images.